Die sinking table



Oct. 25, 1960 o. E. KELM DIE smxms TABLE 3 Sheets-Sheet 1 Original FiledNov. 12. 1953 INVENTOR. arm 5. Ka/w GOO- BY WMMM'V J g a fir rag/varsOct. 25, 1960 o. E. KELM DIE SINKING TABLE 3 Sheets-Sheet 2 OriginalFiled Nov. 12, 1953 m K m 5 a N m o. ow v. B J 1 3 I I N *Nf mN om w: Nq

QO 02 v2 OO- HTTORNEYS' DIE SINKING TABLE Continuation of applicationfier. No. 391,466, Nov. 12, 1953. This application Oct. 18, 1957, Ser.No.

. 33Claims. (Cl. 74-405) This invention relates to a Work positioningand holding device for use with a machine tool and it relatesparticularly to micrometric adjustment structure in said device whichcan be engaged and disengaged from driving relationship whilemaintaining an extremely high degree of precision when in drivingposition. This application is a continuation of Serial Number 391,466,filed on November 12, 1953, and now abandoned, and entitled Die SinkingTable.

In the manufacture of dies or molds from metal, it is necessary that ahigh degree of accuracy be practiced in order that the contours of thedie and its dimensions shall be precise and in accordance withspecifications. The formation of dies and molds requires that many typesof cuts be taken upon the block from which the die is being made. Inmost instances this requires the transfer of the workpiece from machineto machine or from one location upon the work table of a machine toanother location thereon, in order to bring the cutting tool of themachine into proper orientation with the block from which the die isbeing formed. A small proportion of shops are equipped with special veryexpensive machines which make possible the manipulation of the cuttingtool of the machine with respect to the workpiece. The rotary headmilling machine built by Kearney and Treacker of Milwaukee, Wisconsin,is a machine of this character.

Because of the high cost of the special machines which offer suchadjustment possibilities, most die sinking establishments must rely uponthe use of a less expensive and less versatile machine tool, such as avertical milling machine which is standard equipment in most shops, toaccomplish the same result. Where such a machine is used for die making,it is often necessary to move the workpiece several times with respectto the machine during the machining operation, and then reorient saidworkpiece with requisite accuracy at each location, which consumes agreat deal of time. Thus, in a small shop which is not equipped withadjustable machinery to effect relative orientation of the work withrespect to a cutter Without requiring dismantling of the workpiece fromthe machine, a very high proportion of the cost of making a die isinvolved in the non-productive Work of transferring the workpiece.Consequently, small die shops are placed at a substantial disadvantage'in competing with larger shops having the special equipment, inaddition to which the possibility of error or spoilage of the work isincreased greatly because of, and in substantially direct proportion to,the number of times the workpiece must be physically removed from, ormoved around, the machine.

A further problem in the design of work positioning devices of thegeneral type here dealt with lies in the provision of release mechanismwhereby the work posi- A 2,957,362 Patented Oct- 2 1960 tioningstructure of the device can be rotated freely when desired in additionto being rotatable under the influence of a micrometrically arrangedworm. Previous designs have recognized this problem and have endeavoredto solve it by providing eccentrically mounted means for supporting theworm and moving it when desired away from engagement with a worm wheelon the positioning means. However, this apparatus, without more, has inthe past led to inaccuracies and/or binding of the worm and worm wheel.The inaccuracies have previously been believed to exist merely inunremovable tolerances existing in the apparatus as a whole and,accordingly, it was believed that the only way to improve the accuracyof the device was to limit still further the tolerances under which itwas manufactured. However, my investigations have shown that a portionof such inaccuracies arose from the inability of previous mechanisms tomove the worm into precisely the proper relationship with the worm wheelduring successive operations of said mechanisms, and hence there waseither permitted a slight backlash of varying amounts or an undesirablebinding between the worm and worm wheel.

To overcome this defect, I have provided an extremely simple andeffective mechanism by which the movement of the worm toward the wormwheel is precisely controllable by means which always insures engagementof the worm with the worm wheel in exactly the same relationship eachtime such engagement is made. Further, this control means has been madeadjustable so that as the worm and worm wheel wear, suitablecompensation for such wear can be'made so that both backlash and bindingbetween the parts can be prevented. In this way the accuracy of theover-all work positioning device has been greatly increased withoutproviding the worm and worm wheel connections and release mechanismtherefor with the extremely accurate and costly tolerances which wouldotherwise be required to produce the same results.

It is the primary object of this invention to provide a simple andcomparatively inexpensive device which may be applied to a conventionalmachine tool, such as a vertical milling machine, to make possible themounting .of a workpiece upon that machine for substantially universalmovement under a high degree of accuracy so that a workpiece may beadjusted in any of a number of directions with reference to a cutterwithout requiring dismantling of the workpiece from the machine tool.

A further object is to provide a device of this character having a baseand a member rotatable on that base and adapted to be advancedrotatively by drive means operating substantially micrometrically, whichdrive means are characterized by mechanism for throwing the same out ofengagement with the rotatable member so that the rotatable member may beturned to any extent desired by direct manual rotation, without resortto rotation of the worm or hand wheel attached thereto, to facilitatethe positioning of a workpiece mounted upon said rotatable member, butwithout sacrificing the micrometric adjustment desired for high accuracyof machining operations.

A further object of this invention is to provide brake means inassociation with a rotatable member so constructed as to lock therotating member at any selected types of cuts in metal, such as climbingon A further object of this invention is the provision of a device, asaforesaid, having mechanism to reduce, and

compensate for, wear in the drive means for the rotatable member, andhaving structure whereby the position indicators, on those members ofthe device which move to position the work piece, can be easily observedat all times.

Other objects will be apparent from the following specification.

In the drawings:

Figure 1 is a front view of the device with parts broken away.

Figure 2 is a vertical sectional view taken on line 11-11 of Figure 3.

Figure 3 is a top view of the device with parts broken away andillustrated in section.

Figure 4 is a detail sectional view taken on line IV-IV of Figure 3.

Figure 5 is a sectional view taken along the line V--V of Figure 3.

For convenience in description, the terms upper, lower and derivativesthereof will have reference to the device of the invention in its normalposition of operation, as appearing in Figures 1 and 2. The term frontshall have reference to that side of the device shown in Figure 1.

Referring to Figures 1 and 2 in the drawings, which illustrate a workpositioning device 8 embodying the invention, the numeral 10 designatesa base member which is provided with flanges 12 and which is slotted asat 14 to accommodate or register with the ways of grooves 16 (Figure 3)upon the table 18 of a conventional vertical milling machine of the typehaving a vertical machine spindle (not shown) adapted to carry a cuttingtool (not shown). The base member 10 is adapted to be bolted orotherwise anchored to the table 18 as by means of bolts 20 havingT-shaped heads adapted to be received in the T-shaped ways or grooves 16of the table 18. Said bolts 20 have mounting nuts 22 which clamp theflanges 12 in fixed relation with the table 18.

The base member 10 (Figure 2) has a central upwardly projecting andintegral cylindrical portion 24 outlining a coaxial, cylindrical opening25, which is adapted to be releasably closed by a bottom closure plate26. Upright walls 28 are provided at the front, back and two sides ofsaid base 10 and terminate in an inwardly directed top flange or plateportion 30 having a central opening substantially concentric with thecylindrical portion 24. A circular rotatable disk member 32 has amarginal portion whose lower surface bears slidably upon the top surfaceof the plate 30 on the base member. The disk 32 has a central dependinghub 34 which extends into the opening 25 and whose outer diameter issmaller than the diameter of said opening 25. A cylindrical downwardlyprojecting flange 36 is carried by the disk 32 between, and concentricwith, the hub 34 and wall of the aperture in the top plate 30. A bearingmember 38 of any suitable character, here shown as a roller bearing,fits within the cylindrical opening 25 of the base to journal and centerthe hub 34 of the rotatable member 32 therein. The lower end portion ofthe hub 34 is preferably screw-threaded and an adjusting or locking nut40 is threaded thereon to retain the rotatable member 32 in operativeassembled relation to the base member.

The depending flange 36 (Figure 2) of the disk 32 has gear teeth 42 cutin its outer periphery to constitute a worm gear. A worm 44 (Figure 3)is preferably integral with the worm shaft 48. Front and rearcylindrical journal members 52 are journaled in cylindrical bores 53 inthe flange or thickened portions 54 of the vertical walls 28 of the basemember. Each of the journal members 52 has a bore 56 therein, which islocated eccentrically thereof and adapted to receive a portion of theshaft 48. The confronting ends of the journal members 52 havecounterbores 58 which receive bearings 60, such as roller bearings,serving to journal the shaft 48 within the members 52. The front journalmember 52 will preferably have a worm shaft bearing sleeve 62cooperating with the bearing 60 to journal the shaft 48 which extendscompletely and loosely through the bore 56 of the front member 52.

A front cap or plate 64 is secured to the front wall 28 in line with thefront member 52 and serves to hold said front member 52 againstdisplacement. The plate 64 has a hub portion having a large cylindricalpassage 66 therein of a diameter substantially greater than the diameterof the shaft 48, for purposes to be mentioned. The shaft 48 passesthrough the opening 66 to project forwardly of the plate 64. A graduatedcollar 68 having a bearing sleeve 70 thereon is anchored on the shaft 48by means of a thumb screw 72. The shaft 48 has a squared end portion 74,projecting frontwardly from the graduated micrometer collar 68, uponwhich a hand wheel 76 or other drive means may be mounted to rotate theshaft 48.

The wall portions 54 (Figure 3) of the base member have vertical bores78 and 79 formed therein which are in partially intersecting relation tothe horizontal bores 53 which receive the eccentric cylindrical members52, as best seen in Figure 4. Each of the bores 78 and 79 has a lockingnut 80 mounted in the lower part thereof and provided with a tapered orbeveled surface 82 adapted to engage a portion of the surface of theadjacent cylindrical member 52. A bushing 84 is mounted in the upperportion of the bore 78 and it likewise has a tapered surface 86 adaptedto engage the surface of the member 52. A screw-threaded member 88passes slidably through the bushing 84 for screw-threaded engagementwith the nut 80. The member 88 projects above the top plate 30 of thebase member, as does the bushing 84, and a hub portion 90 of a lever 92is secured upon the upper end of the member 88 and is adapted to bearagainst the top surface of the bushing 84. Rotation of the member 88 inone direction will serve to draw the bushing 84 and the screw-threadednut 80 toward each other so that their surfaces 82 and 86 will be urgedinto firm clamping engagement with adjacent member 52, thereby servingto lock that member against rotation in its bore 53.

A horizontal shaft 94 (Figure 3) extends substantially parallel with andalongside the shaft 48, being journaled in openings 95 formed in thewall portions 54 0f the base. The front and rear surfaces of the wallportions 54 are provided with counterbored sockets 96 around theopenings 95, and gear sectors 98 and 98a, which are pinned or otherwisesecured to the shaft 94, fit in the sockets 96. The cylindrical members52 have gear teeth 100 out in the ends thereof with which the teeth ofthe gear sectors 98 and 98a mesh. The gear sector 98 (Figure 5) has aradially disposed surface 93 adjacent to its periphery and at thecounterclockwise end of a circumferentially elongated and arcuate recess99 in said periphery. An adjustment screw 97, which extends upwardlythrough, and is threadedly engaged by, a threaded opening in the wallportion 54, engages at its upper end the surface 93 on the gear sector98 to adjustably limit the clockwise rotation of said sector, asappearing in Figure 5. A set screw 101 releasably holds the adjustmentscrew 97, as desired. Engagement of the worm 44 with the worm gear 42 iscontrolled by engagement between the surface 93 and the adjustment screw97.

The shaft 94 projects forwardly from the base member through an aperturein the front plate 64 and mounts a hub 102 of an operating lever 104 bymeans of which the shaft 94 may be rotated. A rear closure plate 106 ismounted on the rear wall 28 and serves as a retainer to confine the rearmember 52 and the rear sector gear 98a in operative relation to the basemember. A plug 107 is threaded in plate 106 to take up the end play ofthe rear member 52.

A brake shoe 110 (Figures 2 and 3), which is split at 112, fits withinthe depending cylindrical flange 36 j and has projecting ear portions114 at its opposite ends passing beneath the cylindrical flange 36 toproject outwardly thereof and define cam engaging faces 116. A cam pivotpin 118 is carried by the base member and is positioned between the camfaces 116 to mount a cam member 120. The cam member 120 depends from agear segment 122 which is adapted to mesh with a rack member 124confined and positioned in a rack guide 126 carried by the adjacent sidewall 28 of the base member. The rack has a screw-threaded shaft 128secured thereto and slidably extending through an appropriate opening129 in the front wall 28. A hub portion 130 is threadedly engaged withthe end of said shaft projecting forwardly from the front wall 28, andsaid hub 130 is rotatably held against axial movement by a retainer 132.

A hand wheel 134 is carried by the hub 130 and serves to move the shaft128 axially and thereby pivot the rack 124 about the pin 118. This movesthe cam 120 for the purpose of spreading the cam faces 116 on the splitbrake shoe 110 to expand and contract the same relative to thecylindrical part 36 of the rotatable member 32. In other words, byrotating the hand wheel 134 in a direction to cause the cam 120 tospread the cam faces 116 of the brake shoe 110, the brake shoe 110 isexpanded into making frictional engagement with the inner surface of thecylindrical flange 36 so as to positively and firmly brake and hold themember 32 against rotative movement. Reverse rotation. of the hand wheel134 serves to release the braking action preparatory to operation of thehand wheel 76 for the purpose of rotating the worm 44 and the gear 42 soas to rotate the rotatable member 32.

A pointer plate 136 (Figure 1), having an adjustment knob 138 associatedtherewith, is carried by the base member in a position to extendalongside the lower peripheral portion of the rotatable member 32. Thismember 32 is provided with a graduated scale 141) on its periphery foraccurate measurement of the angular displacement of the member 32 from azero setting. The periphery of the member 32 is preferably grooved at142 as by means of a T-slot, as best seen in Figure 2, within which anadjustable rotation stop member 144 may be anchored at any selectedposition by means of the screw 146. The top plate of the base member maymount a block 148 adjacent the periphery of the member 32 and extendinginto the path of the member 144 so as to limit the rotative movement ofthe rotatable member if desired. It will be understood that the parts144 and 148 are optional.

A pair of spaced slide guides 150 (Figure 1), having undercut opposingfaces, are fixedly carried by the rotatable member 32 at the topthereof. An intermediate cross-slide member 156 bears upon the members150 and has an integral and elongated dovetail 158 on its lower sidewhich is in interlocking engagement with said guides 150. A topcross-slide member 166 (Figure 2) is mounted slidably upon theintermediate slide member 156 and has a dovetail 162 arranged ininterlocking engagement with the guides 157 on said member 156. Saiddovetail 162 extends horizontally and perpendicularly to the dovetail158. The top slide member 160 will preferably be provided with T-slots166 of the. character well understood in the art to accommodateanchorage of work pieces thereon by the use of bolts having T-shapedheads. A stop 155 is mounted on the rotatable member 32 and isengageable with intermediate cross-slide memher 156 to limit movementthereof. The stop 155 may be moved out of the way by loosening the boltwhich holds same on member 22 and then rotating same sidewardly.Alternatively, the stop may be entirely removed from member 32.

A gib 152 (Figure l) is disposed between the dovetail 158 and one of theslide guides 150, and a gib adjusting screw 154 operates on the gib tocontrol the sliding tolerances or lock the slide in a conventionalmanner. A gib member 168 (Figure 2) is interposed between the dovetail162 and one of the slide guides 157 on the intermediate slide member156. Said gib 168 is engaged by one end of a locking thrust shoe 170slidably disposed in a bore in the member 156 and in turn engaged by anequalizing ball 172 within the lock-receiving bore 171, which ball inturn is pressed upon by the slide lock screw 174 screw-threaded in saidbore 171.

The adjusting mechanism 176 between the intermediate slide member 156and the rotatable member 32 is substantially the same as the adjustingmechanism 178 between the top slide 160 and the intermediate slide 156.Thus, parts of the adjusting mechanism 178 (Figures 1 and 2) will beidentified by the same reference numerals as corresponding parts inmechanism 176, in addition to the suffix a.

A feed nut 188 is mounted on each of the rotatable member 32 and theintermediate slide 156, the same being displaced degrees with respect totheiraxes, and preferably being held accurately in that position bymeans of dowels 182 or like securing and positioning members. Each ofthe intermediate slide and the top slide is recessed at 184 to provideclearance for the associated feed nut. End caps or plates 186 aresecured to the slide members 156 and 160 to span and partially close thepassages 1.84 thereof. Each of the end caps 186 mounts a bearing 188which journals the reduced end portion of a cross feed screw 1%. Agrease retaining washer 112 bears against the shoulder at the end of thecross feed screw 1% and against the bearing 188 at one side of thatbearing. At the other side of that bearing a bearing adjusting nut 194is screw-threaded into the plate 186. Hand knobs 196 are keyed at 198 toboth ends of the feed screw 190, and the knobs 196 have micrometercollars 2110 mounted thereon. A hand Wheel 2112 may be mounted upon oneend of the screw 190.

The two slides 156 and 168 (Figure 1) support scale members 284 and2114a, respectively, which are adapted to be read in correlation withpointer plates 206 and 286a mounted upon the slide 156 and disk member32, respectively. Thus, the pointer plate 206a, which is read inassociation with the scale 284a upon the top slide 160, is mounted uponthe intermediate slide 156, while the pointer plate 2116, which isadapted to be read in association with the scale 204 on the intermediateslide 156, is mounted upon the guide which is carried by the rotatablemember 32.

In the use of the device the base member is mounted upon means, such asa movable table 18 of a conventional vertical milling machine having avertical machine spindle (not shown). The device will preferably be somounted that the rotatable member 32 will be axially aligned with themachine spindle. Likewise, the cross slide members 156 and willpreferably be centered, that is, will be located at their respectviezero positions, as indicated upon the scales 284 and 204a and themicrometer scale collars 2M and 20011. The rotatable member 32 will beset at zero as indicated by the angle measuring scale 141i, and upon thegraduated micrometer collar 68 of the worm shaft 48. In other words, thecomplete unit is precisely and centrally located in relation to thespindle of the machine tool, and all dials of that machine tool willpreferably be set at zero. A work piece is then mounted and located uponthe top slide 160 in a conventional manner using the T-slots 166provided in the top slide as means for anchorage of clamping membershaving T-shaped heads fitting in those slots.

As an aid in manipulating the clamping means, and particularly tofacilitate rotation of the device during location of the work piecerelative to a cutter, it may be desired to release the rotatable member32 for free rotation. That operation can be accomplished simply andrapidly by manipulating the levers 92 in a direction to release theclamping pressure of the bushings 84 and the nuts 88 upon the eccentriccylinders 52. When that clamping action has been released, the lever 104may be swung through an arc to rotate the gear sectors 98 which meshwith the gear teeth 100 on the eccentric members 52 and rotate thoseeccentric members in such a manner as to swing the worm shaft 48 bodilyfrom the position shown in Figure 4 to a position in which the worm 44disengages the gear 42 on the rotatable member 32. Thereupon, the member32 and the parts carried thereby may be rotated freely as the work pieceis secured to the top slide.

When the work piece has been properly secured in place, the rotatablemember is returned to its zero position, and the lever 104 (Figure 3) ismoved to rotate the shaft 94 in a counterclockwise direction asappearing in Figure 5, whereby the gear sectors 98 and 98a are alsorotated counterclockwise. This results in a clockwise rotation of thejournal members 52 which, due to the eccentric support of the worm 44 bysaid journal members, causes the worm to move toward the worm gear 42until the surface 93 on gear sector 98 engages the adjustment screw 97,at which point the worm will normally engage the worm gear. It there isa binding between the worm 44 and the gear 42 the set screw 101 isloosened and the adjustment screw 97 is moved upwardly against thesurface 93, thereby increasing the center line distance between the Wormand worm gear until the binding is relieved. If the engagement betweenthe worm 44 and gear 42 becomes loose as a result of wear, for example,thereby produicng backlash, the adjustment screw is lowered, whichproduces a reduction in the centerline distance between the worm andworm gear. In both instances, the adjustments can be made precisely andaccurately in extremely small increments and at any time that suchadjustments appear to be desired or required.

After the worm 44 has been reengaged with the worm gear, the members 52are locked in operative position by moving the levers 92 to cause firmfrictional locking engagement of the members 52 by the locking bushings84 and the locking nuts 80. Thereafter, as any rotative adjustment isdesired in the position of the member 32, it can be effected byoperation of the hand wheel 76 and can be controlled with micrometricaccuracy through the angle scale 140 and the micrometer scale 68.

Once a desired rotative position of the member 32 has been set, themember 32 can be locked in that setting by turning the hand wheel 134.This rotates the shaft 128 for the purposes of advancing the rack 124 inits guide 126 and thereby swinging the gear segment 122 having the cam120 associated therewith. The rotative movement of the cam 120 actingagainst the surfaces 116 on the ears 114 of the brake shoe 110 serves toexpand that brake shoe into firm frictional engagement with the innersurface of the flange 36 on the rotatable member. Consequently, throughthe use of this brake no possible rotation of the member 32 can occur.Furthermore, this brake serves as an additional means to steady therotatable member relative to the base and its mounting and to avoid theoccurrence of chattering and vibration incident to the taking of a heavycut or a particular type of cut, such as a climbing out, in whichchattering and vibration are most commonly experienced. As used herein,the term climbing cut means a cut made by feeding work with respect to arotating cutter in the same direction as the peripheral movement of thecutter adjacent to the work.

In addition to the rotative adjustment, the work piece may be adjustedrelative to the cutting tool on the machine spindle by the cross slidemembers 156 and 160'. Furthermore, if the table 18 of the machine tool,such as a mill upon which this mechanism is mounted, is adjustable, themoving of that table 18 affords a further adjustment of the work piece.It will be evident that the adjustments of the slides 156 and 160 may beaccomplished with micrometric accuracy by observing the scales 204 and204a and also the micrometer collars 200 and 200a. Thus the position ofthe work piece with relation to the machine spindle may be alteredthrough a wide range of movements without requiring disconnection of thework piece from the top slide member and, particularly, withoutrelocating the device of the invention with respect tothe table 18.Obviously, the various movements of the parts, that is, the rotation ofthe member 32 and the movement of either of the slides 156 and 160, mayoccur while a cut is being taken by a machine tool and thus accurateguidance of intricate cutting of contours may be accomplished.Alternatively, the adjustment may be effected while the cutting tool isout of engagement with the work, as in instances where holes are to bedrilled at selected points or other special cuts are to be taken atpredetermined points spaced from previous cuts.

The device is characterized by case and accuracy of manipulation andmeasurement, simplicity of use, sturdiness and firm location of parts,locking against vibration or chattering in use, and ready maneuvering orrotation to facilitate connection or disconnection of a work piece. Withreference to avoidance of chatter, attention is directed to theprovision of a gib adjusting means which insures freedom of movementwhile preventing play at the dovetailed joints between the relativelyslidable members, and which acts further as means to permit positivelocking of the slides to each other and to the rotatable member at aselected position while a machining operation is being performed.

While the preferred embodiment of the invention has been illustrated anddescribed, it will be understood that changes in the construction may bemade within the scope of the appended claims without departing from thespirit of the invention.

I claim:

1. In a rotary, work-supporting table structure including a base, atable rotatably mounted on said base, a work wheel coaxially secured tosaid table, a worm rotatably supported in eccentric openings in journalsso that said worm can be moved into or out of engagement with said wormwheel by rotation of said journals, the combination with said tablestructure of mechanism for effecting rotation of said journals and forlocating same in a precisely adjustable position when said worm and saidworm wheel are in engagement which comprises gear teeth on said journalsarranged concentric with the axis thereof; a gear engaged with the gearteeth on each of said journals and means for effecting simultaneousrotation of said gears, at least one of said gears being a sector gear,said sector gear having a substantially radially disposed stop surfaceadjacent the periphery thereof; adjustable stop means mounted in saidbase for engaging said stop surface to prevent rotation of said gears inone direction and thereby prevent rotation of said journals in onedirection when said worm engages said worm wheel, whereby said worm andsaid worm wheel can be repetitively engaged in the same relationshipwith each other; and locking members supported within said baserespectively adjacent to said journals, said locking members beingreleasably engageable with said journals for selectively preventingrotation thereof.

2. The structure of claim 1 wherein said gears are mounted upon a shaftparallel with the rotational axis of said journals, and wherein saidstop means is comprise-d of a screw threadedly disposed in said base formovement along and around an axis substantially perpendicular to saidstop surface when said worm is in engagement with said worm wheel.

3. The structure of claim 1 wherein said gears are mounted upon a shaftparallel with the rotational axis of said journals; wherein said lockingmembers comprise a pair of spaced sleeves disposed in said base foraxial movement along a common axis substantially perpendicular to aplane defined by the axes of said worm and said journals, said sleevesbeing on opposite sides of said plane and engageable at their adjacentends with one journal; and wherein there is included a manuallycontrollable screw extending through said sleeves, for

moving said sleeves toward and away from said one journal.

References Cited in the file of this patent UNITED STATES PATENTS SengerMay 31, 1938 10 Gorham Nov. 8, 1938 Senger Feb. 28, 1939 Nicolls Mar.11, 1952 Costello June 5, 1956 Wahlstrom Nov. 20, 1956 Coy Jan. 14, 1958FOREIGN PATENTS .Great Britain Feb. 22, 1909 Italy Nov. 6, 1937 FranceOct. 4, 1920

